Many hydrohalofluoroolefins can exist as E/Z isomers according to the arrangement of substituents around the double bond. In general, E/Z isomers have different physical characteristics and chemical characteristics. Therefore, in particular uses, one isomer may be preferable to the other. From this, in some cases, it is preferable to be able to convert one E/Z isomer to the other E/Z isomer.
Under such background, there have been tried mutual conversions by isomerization of hydrohalofluoroolefins. It is described in Patent Publication 1 that the ratio of cis isomer to trans isomer of 1,2,3,3,3-pentafluoropropene can be increased and decreased and that this can be conducted by using a catalyst supported on AlF3 or carbon. This catalyst is selected from SbClwF5-w, TiClxF4-x, SnClyF4-y, and TaClzF5-z, wherein w is 0-4, x is 0-3, y is 0-3, and z is 0-4. Furthermore, in Patent Publication 2, there is described a partial isomerization from E-1,3,3,3-tetrafluoropropene to Z-1,3,3,3-tetrafluoropropene on a crushed, chromium oxide gel pellets catalyst.
In Patent Publication 3, there is disclosed a process in which a catalyst, such as a Lewis acid catalyst or a chromia-containing catalyst, is contacted with a E-(hydro)halofluoroalkene, thereby isomerizing the same into the Z-(hydro)halofluoroalkene by using an equilibrium reaction.
In Patent Publication 4, there is disclosed a method for producing Z-1,3,3,3-tetrafluoropropene from E-1,3,3,3-tetrafluoropropene by using a metal-containing, metal compound, etc. as the catalyst.
In Patent Publication 5, there is disclosed a method for producing E-1,3,3,3-tetrafluoropropene from Z-1,3,3,3-tetrafluoropropene by using a metal oxide, its partially fluorinated compound, or its totally fluorinated compound, etc. as the catalyst.